Research On Cycle Slip Detection Method For GPS Single-point Positioning

To realize high-precision global navigation and positioning is the inherent requirement of the development of the times and the progress of science and technology.Therefore,the pseudo-range positioning method with large errors can no longer meet the needs of high precision,while the carrier can achieve high-precision positioning due to the advantages of shorter cycle length and smaller error.However,due to the existence of cycle slips in the observed carrier phase data,the positioning accuracy will be reduced,and the cycle slip detection method needs to be used to determine the epoch and size of cycle slip occurrence.In this paper,the research on the cycle slip detection method for GPS single-point positioning is carried out,mainly including the following aspects:(1)Aiming at the problem that the single-frequency cycle slip detection code-phase combination method cannot detect small cycle slips due to high noise,this paper adopts the method of constructing the detection signal into a matrix and performing singular value decomposition to reduce the impact of noise,by selecting different matrices form and effective order determination methods to improve the effectiveness of singular value decomposition method,and thresholds are independently designed to detect cycle slips.The simulation results show that the matrix form and the effective order determination method adopted in this paper are better than the usual methods in detecting cycle slip,and the self-designed threshold method is reasonable.(2)Aiming at the situation that the ionospheric residual method may mistakenly detect the cycle slip when the sampling interval is large and the ionosphere changes actively,this paper obtains the code-phase combination in the form of eliminating ionospheric residual by using the combination of geometry-free(GF)pseudo-range instead of the ionospheric influence,and deduces the code-phase combination without ionosphere by calculating the coefficient.The two are linearly combined according to the ratio of the size of the noise contained in the two code-phase combinations,forming the dual-frequency cycle slip detection method that is not affected by the ionosphere and sampling interval.The simulation results show that the method has good detection effect on all cycle slips except the insensitive ones.(3)Because of the selection process of three sets of linearly independent code-phase combinations is complicated,and the conditions of minimum pseudo-range noise and wavelength length are limited,the detection effect of the three sets of carrier combination coefficients will decline sequentially.This paper proposes a set of optimal code-phase combination is selected through the factors such as noise,ionospheric error and wavelength joint tri-frequency ionospheric residual method to detect cycle slips,which can achieve accurate detection of tri-frequency cycle slips.The experiment shows that although both methods have their own detection blind spots,the combination of them can detect any tri-frequency combined cycle slips,and the detection effect is good.